The 3rd Generation Partnership Project (3GPP), which is a standardization project, has standardized the Evolved Universal Terrestrial Radio Access (EUTRA), in which high-speed communication is realized by adopting an orthogonal frequency division multiplexing (OFDM) communication scheme and flexible scheduling in a unit of prescribed frequency and time called a resource block. EUTRA may be also referred to as Long Term Evolution (LTE).
The 3GPP discusses LTE Advanced (also referred to as LTE-A), which realizes higher-speed data transfer and has compatibility with LTE. According to the LTE Advanced, a technology of simultaneously connecting with multiple cells to perform communication (a carrier aggregation technology or a dual connectivity technology) is described (NPL 1).
NPL 2 discusses Licensed-Assisted Access (LAA). The LAA is a technology that uses a frequency of an unlicensed spectrum used by a radio Local Area Network (LAN) or the like, as LTE in an assisted manner. More specifically, a terminal device and a base station device add a cell (secondary cell) of a frequency in the unlicensed spectrum in addition to a cell (primary cell (described below)) of a frequency in a licensed spectrum by the carrier aggregation technology to perform communication. The frequency of the unlicensed spectrum is, for example, an Industry-Science-Medical (ISM) band.